I have always thought of it as ratios, with 1:31 yielding 32 parts with HC-110.

1:1 as a stock solution without dilution just makes zero sense to me. Better (IMO) to use 1+0, or 1:0, but best to just say "stock solution".

Disclaimer -- I am not a chemist. I am more use to thinking in terms of mathematics, and of roof pitches and steepness of trails where 2:9 is 2 units of rise to every 9 units of run).